For example, in an endoscope for medical use, a combination of a xenon lamp and rotating RGB color disk is conventionally known as a light source for illuminating a subject. However, there was a problem that the configuration was expensive and the configuration of the light source itself was complicated.
Therefore, there is proposed a light source device which solves the above problem by using R, G, and B light-emitting elements and sequentially pulsatively lighting the light-emitting elements in synchronism with an exposure period of the image pickup device at the rated level instead of using the xenon lamp and rotating RGB color disk as the light source device. One example of the light source device is disclosed in Jpn. Pat. Appln. KOKAI Publication No. H11-225953.